Field of the Invention
The present disclosure relates to a resin-mold core having a magnetic core embedded in a resin-mold component by molding like insert molding, and a reactor using the same.
Description of the Related Art
As a reactor utilized for, for example, an in-vehicle booster circuit, one which has a resin bobbin disposed at a leg portion of an annular magnetic core, and which has a coil wound around this bobbin is conventionally known. According to this type of reactor, as a technology of disposing the bobbin around the magnetic core, insert molding of the magnetic core in the resin bobbin is known.
In this case, not only the leg portion of the magnetic core is covered by the bobbin, but also the yoke portion of the magnetic core is covered by the resin integral with the bobbin in order to ensure the insulation of the yoke portion. A core having the leg portion and the yoke portion having undergone insert molding in the resin integral with the bobbin is generally called a resin-mold core, and disclosed in, for example, JP2013-149869 A, JP2013-149868 A, JP2013-012643 A and JP2010-238798 A.
When manufacturing the resin-mold core, a resin is filled around the magnetic core set in a die and is cured. At this time, it is necessary to support and lift up the magnetic core in the die so as to form a space around the magnetic core where the resin is filled. Hence, a protrusion (also called a spacer) that is a support member is provided at a part of the die, and the surface of the magnetic core is caused to contact the protrusion, and the magnetic core is supported in this way in the die.
According to a resin-mold core 100 obtained thus way, for example, as illustrated in FIG. 15, a portion corresponding to the protrusion of the die in an external resin-mold component 101 becomes an opening 102 where no resin is filled, and exposes a magnetic core 103 in the resin-mold component 101. In this case, in order to position the magnetic core at the center of the die, it is preferable to provide the protrusions around the entire circumference of the magnetic core, i.e., six surfaces which are the upper and lower, front and rear, and right and left surfaces of the magnetic core 103 from the standpoint of precise positioning. According to the conventional technology, the openings 102 are formed in all six surfaces of the resin-mold core.
When a reactor is manufactured using this type of resin-mold core, coils wound beforehand in a cylindrical shape are fitted to outer circumferences of respective leg portions 104 of the resin-mold core, and a terminal to connect the coil to an external wiring is connected to an end of each coil. In this case, since the connection terminals are connected to both ends of the coil, the terminal is typically drawn to the exterior through the yoke-portion side of the resin-mold core.
According to the conventional resin-mold core, the openings 102 are formed in all six surfaces of the resin-mold component 101. Accordingly, the opening 102 is also provided on a resin portion 109 covering the yoke portion, and the magnetic core 103 is exposed. Hence, when the terminal is drawn to the yoke-portion side from the end of the coil, it is difficult to ensure the insulation because of the opening 102 formed at the yoke portion. As a result, it is necessary to dispose the terminal so as to avoid the opening 102, and to provide another member that insulates the magnetic core 103 exposed at the opening 102 from the terminal.
When, however, the terminal is disposed so as to avoid the opening 102, the drawing direction of the terminal is restricted, and the downsizing of the reactor becomes difficult. In addition, when another insulation member is provided, the number of components of the reactor increases, and the number of assembling steps thereof increases.
The present disclosure has been made in order to address the above-explained problems of the conventional technology. It is an objective of the present disclosure to provide a resin-mold core which has no opening where a magnetic core is exposed at a yoke portion corresponding to a terminal drawing location, and which ensures an excellent insulation performance between the magnetic core and the terminal at the yoke portion.
It is another objective of the present disclosure to provide a reactor which uses the above-explained resin-mold core with an excellent insulation performance to improve the degree of freedom for a terminal drawing direction, and to reduce the number of components, thus enabling downsizing.